Electrotonic junctions will be studied in respect to their physiological properties and ultrastructural features in a variety of tissues including embryonic cells. Characteristics of the hydrophilic channel in these junctions will also be examined. Development of abnormal membrane structure and function of neurons in feline GM1-gangliosidosis will be studied. Morphophysiological studies of neuronal interaction will employ the Mauthner fiber-giant fiber synapse of the hatchetfish and frog neuromuscular junctions to analyze the comparative neurobiology of synaptic vesicle-transmitter release relations. Electroreceptors will provide the basis for an investigation into the operation of secondary receptors and their transmitter release mechanisms. The morphological features of rectifying electrotonic junctions will be studied with freeze-fracture techniques. Feeding behavior in the opistobranch, Navanax will be analyzed at the cellular level of synaptic organization.